BET 1: Green or blue for you? Methoxyflurane (Penthrox) or nitrous oxide/oxygen 50% mixture (Entonox) for the management of acute pain in the ED.

A short-cut review of the literature was carried out to establish whether inhaled methoxyflurane (Penthrox) is comparable or superior with a standard inhalational analgesia for the management of acute pain. Only two papers were identified as suitable for inclusion using the reported search strategy. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of the best papers are tabulated. It is concluded that both methods of inhaled analgesia appear to be useful options for acute pain in the ED when compared with placebo. No evidence was found to suggest superiority of methoxypenflurane. International studies directly comparing the use of both drugs for in acute trauma are ongoing and will develop the evidence base.

Quality Control: Lessons Learned from a Trimix Stability Study in a 503A Compounding Pharmacy.

Changes in California regulations regarding beyond-use dates of sterile preparations have prompted many compounders to consider stability studies for their formulas. Traditionally, 503A compounders have relied on published data and professional experience to determine stability. However, due to these new regulations, stability studies are now required for California resident and nonresident licensees to extend the beyond-use date of sterile preparations. Conducting studies for the first time can be costly and difficult for compounding pharmacists. This article shares several lessons learned from the author's experience performing stability studies on Trimix injection, a sterile preparation for erectile dysfunction. Avoiding easily made errors can save the compounder unnecessary time and expense.

Revisiting inland hypoxia: diverse exceedances of dissolved oxygen thresholds for freshwater aquatic life.

Water resources in many regions are stressed by impairments resulting from climate change, population growth and urbanization. In the United States (US), water quality criteria (WQC) and standards (WQS) were established to protect surface waters and associated designated uses, including aquatic life. In inland waters of the south central US, for example, depressed dissolved oxygen (DO) consistently results in impaired aquatic systems due to noncompliance with DO WQC and WQS. In the present study, we systematically examined currently available DO threshold data for freshwater fish and invertebrates and performed probabilistic aquatic hazard assessments with low DO toxicity data that were used to derive the US Environmental Protection Agency's (EPA) Ambient Water Quality Criteria (AWQC) for DO and newly published information. Aquatic hazard assessments predicted acute invertebrate DO thresholds for Ephemeroptera, Plecoptera, or Trichoptera (EPT) taxa and species inhabiting lotic systems to be more sensitive than fish. For example, these organisms were predicted to have acute low DO toxicity thresholds exceeding the US EPA guidelines 17, 26, 31 and 38% and 13, 24, 30 and 39% of the time at 8.0, 5.0, 4.0 and 3.0 mg DO/L, respectively. Based on our analysis, it appears possible that low DO effects to freshwater organisms have been underestimated. We also identified influences of temperature on low DO thresholds and pronounced differences in implementation and assessment of the US EPA AWQC among habitats, seasons, and geographic regions. These results suggest some implemented DO guidelines may adversely affect the survival, growth, and reproduction of freshwater aquatic organisms in a region susceptible to climate change and rapid population growth. Given the global decline of species, particularly invertebrates, low DO threshold information, including sublethal (e.g., reproduction, behavior) responses, for additional species (e.g., mollusks, other invertebrates, warm water fish) across seasons, habitats, and life history stages using consistent experimental designs is needed to support more sustainable environmental assessment efforts and management of biodiversity protection goals in inland waters.

Impact of highly concentrated contaminants on the quality of oxygen 93 % produced by pressure swing adsorption.

A zeolite based pressure swing adsorption (PSA) module designed to produce medicinal oxygen with 90 - 96 % oxygen content was exposed to high input concentrations and high total amounts of CO (17.7 %, 44 mol), CO2 (16.5 %, 23 mol), NO2 (0.98 %, 2 mol), NO (6.2 %, 6 mol) and SO2 (4.2 %, 6 mol). In addition the system was operated with up to 35 % argon in the feed gas. An empirical model was developed to describe the dependence of the oxygen concentration in the product on the oxygen concentration in the input. If the oxygen concentration in the feed gas was reduced below 18 % by dilution, the oxygen concentration in the product fell under the 90 % threshold. Additional effects were observed with NO, NO2 and SO2 which are apparently due to chemical reactions on the adsorbent. These effects consisted of a further decrease in the oxygen concentration measured in the product and could not be reversed by excessive regeneration of the module with air. Under the experimental conditions used, only CO was detected in the product. Appropriate CO monitoring of the input gas is considered a possible remedy for PSA modules in order to ascertain the pharmaceutical quality of the oxygen produced.

Recreational technical diving part 1: an introduction to technical diving methods and activities.

Technical divers use gases other than air and advanced equipment configurations to conduct dives that are deeper and/or longer than typical recreational air dives. The use of oxygen-nitrogen (nitrox) mixes with oxygen fractions higher than air results in longer no-decompression limits for shallow diving, and faster decompression from deeper dives. For depths beyond the air-diving range, technical divers mix helium, a light non-narcotic gas, with nitrogen and oxygen to produce 'trimix'. These blends are tailored to the depth of intended use with a fraction of oxygen calculated to produce an inspired oxygen partial pressure unlikely to cause cerebral oxygen toxicity and a nitrogen fraction calculated to produce a tolerable degree of nitrogen narcosis. A typical deep technical dive will involve the use of trimix at the target depth with changes to gases containing more oxygen and less inert gas during the decompression. Open-circuit scuba may be used to carry and utilise such gases, but this is very wasteful of expensive helium. There is increasing use of closed-circuit 'rebreather' devices. These recycle expired gas and potentially limit gas consumption to a small amount of inert gas to maintain the volume of the breathing circuit during descent and the amount of oxygen metabolised by the diver. This paper reviews the basic approach to planning and execution of dives using these methods to better inform physicians of the physical demands and risks.

Cerebral oximetry during cardiac surgery: the association between cerebral oxygen saturation and perioperative patient variables.

OBJECTIVE: This "real-world" study was designed to assess the patterns of regional cerebral oxygen saturation (rSO(2)) change during adult cardiac surgery. A secondary objective was to determine any relation between perioperative rSO(2) (baseline and during surgery) and patient characteristics or intraoperative variables. DESIGN: Prospective, observational, multicenter, nonrandomized clinical study. SETTING: Cardiac operating rooms at 3 academic medical centers. PARTICIPANTS: Ninety consecutive adult patients presenting for cardiac surgery with or without cardiopulmonary bypass. INTERVENTIONS: Patients received standard care at each institution plus bilateral forehead recordings of cerebral oxygen saturation with the 7600 Regional Oximeter System (Nonin Medical, Plymouth, MN). MEASUREMENTS AND MAIN RESULTS: The average baseline (before induction) rSO(2) was 63.9 ± 8.8% (range 41%-95%); preoperative hematocrit correlated with baseline rSO(2) (0.48% increase for each 1% increase in hematocrit, p = 0.008). The average nadir (lowest recorded rSO(2) for any given patient) was 54.9 ± 6.6% and was correlated with on-pump surgery, baseline rSO(2), and height. Baseline rSO(2) was found to be an independent predictor of length of stay (hazard ratio 1.044, confidence interval 1.02-1.07, for each percentage of baseline rSO(2)). CONCLUSIONS: In cardiac surgical patients, lower baseline rSO(2) value, on-pump surgery, and height were significant predictors of nadir rSO(2), whereas only baseline rSO(2) was a predictor of postoperative length of stay. These findings support previous research on the predictive value of baseline rSO(2) on length of stay and emphasize the need for further research regarding the clinical relevance of baseline rSO(2) and intraoperative changes.

Baseline cerebral oximetry values in elderly patients with hip fractures: a prospective observational study.

AIM: This study was conducted to evaluate baseline cerebral tissue regional oxygen saturation (rSO(2)) values and identify risk factors related to severe rSO(2) reductions in elderly patients with hip fractures. PATIENTS AND METHODS: This was a prospective observational single-centre study on patients undergoing scheduled or urgent operation for isolated hip fracture. The study was approved by the Institution Ethics Committee, and all patients signed informed consent before entering the study. Data were collected on factors potentially related to baseline cerebral rSO(2). Data were analysed with Student's t-test, Pearson's correlation or multiple regression analysis as appropriate. RESULTS: Sixty-nine patients, aged (mean±standard deviation (SD)) 74±13 years participated. Left baseline rSO(2) was 60.09±10.20 and right baseline rSO(2) was 58.64±9.92. Baseline rSO(2)<45 was observed in 10.1% of patients on the left and 8.7% on the right side. Correlation between left- and right-side baseline cerebral rSO(2) was highly significant (r=0.852, p<0.001). Baseline cerebral rSO(2) had a positive, highly significant correlation with preoperative haematocrit (r=0.50, p<0.001) and arterial haemoglobin oxygen saturation (SpO(2)) (r=0.587, p<0.001), but correlation was negative with the American Society of Anesthesiologists (ASA) physical status (r=-0.42, p<0.001) and age (r=-0.39, p=0.001). Linear regression showed that preoperative haematocrit accounts for 23% (R(2)=0.23) of baseline rSO(2) variability, whereas preoperative haematocrit and SpO(2) combined account for 43.7% of rSO(2) variability (R(2)=0.437). Combined preoperative haematocrit+SpO(2)+age accounted for 51.3% (R(2)=0.513) of observed rSO(2) variability. CONCLUSION: Low baseline cerebral rSO(2) values are common in elderly hip fracture patients, despite normal haemodynamic and arterial saturation values. Preoperative haematocrit, SpO(2) and age explain a significant portion of cerebral rSO(2) variability. More studies are needed to validate our findings and assess the potential benefit of interventions aimed at improving cerebral rSO(2) in elderly hip fracture patients.

An interlaboratory study as useful tool for proficiency testing of chemical oxygen demand measurements using solid substrates and liquid samples with high suspended solid content.

In 2008, the first Proficiency Testing Scheme of Chemical Oxygen Demand (1(st)COD-PT(ADG)) was conducted to assess the results obtained for different research groups whose field work is mainly anaerobic digestion. This study was performed using four samples, two solid samples as raw materials and two solid samples to prepare high concentration suspended solid solutions. Invitations were sent to a large number of laboratories, mainly to anaerobic digestion research groups. Finally, thirty labs from sixteen countries agreed to participate, but for different reasons four participants could not send any data. In total, twenty-six results were reported to the COD-PT coordinator. This study showed the importance of continuous participation in proficiency testing (PT) schemes in order to compare the results obtained. Taking into account the lack of a general standard method and high quality certified reference materials (CRMs), the traceability of COD determination is not currently easy to check. In addition, the spread of participants' results obtained was high and pointed to the advisability of using consensus values due to their unreliability. Therefore, the theoretical oxygen demand (ThOD) values were considered as assigned values for all the samples analysed. On the other hand, in this PT the established standard deviation (ESD) has been determined by the Horwitz modified function. Participants of this 1(st)COD-PT(ADG) were asked to give a short report on the analytical method used. Although all the participants used potassium dichromate as their oxidant reagent, their experimental procedures were very different. With the purpose of comparing the results obtained, the different experimental conditions used were classified into five methods, corresponding to two main categories, open and closed reflux. The performance of laboratories was expressed by the z-score, whose value is considered satisfactory when z-score

Air contaminants in a submarine equipped with air independent propulsion.

The Swedish Navy has operated submarines equipped with air independent propulsion for two decades. This type of submarine can stay submerged for periods far longer than other non-nuclear submarines are capable of. The air quality during longer periods of submersion has so far not been thoroughly investigated. This study presents results for a number of air quality parameters obtained during more than one week of continuous submerged operation. The measured parameters are pressure, temperature, relative humidity, oxygen, carbon dioxide, hydrogen, formaldehyde and other volatile organic compounds, ozone, nitrogen dioxide, particulate matter and microbiological contaminants. The measurements of airborne particles demonstrate that air pollutants typically occur at a low baseline level due to high air exchange rates and efficient air-cleaning devices. However, short-lived peaks with comparatively high concentrations occur, several of the sources for these have been identified. The concentrations of the pollutants measured in this study do not indicate a build-up of hazardous compounds during eight days of submersion. It is reasonable to assume that a substantial build-up of the investigated contaminants is not likely if the submersion period is prolonged several times, which is the case for modern submarines equipped with air independent propulsion.

Risk assessment of physico-chemical contaminants in groundwater of Pettavaithalai area, Tiruchirappalli, Tamilnadu - India.

A study was carried out in Pettavaithalai area to evaluate the current status of physico-chemical contaminants and their sources in groundwater. Groundwater samples collected from pettavaithalai area in 15 different stations were analyzed every alternative months over a period of two years from August 2000 to June 2002. A sugar mill is situated at the heart of the study area. Three profiles (profile A, B and C) were selected based on the direction in which the sugar mill effluent flows. In each profile five samples were collected from five different station at a regular distance of about 1 Km. The physico-chemical parameters such as pH, EC TDS, TH, NO3, SO4, PO4, Na, K, Ca, Mg, DO, BOD and COD have been analyzed. The results showed that among the three profiles, many of the estimated physico-chemical parameters of profile C were very high when compared to profile B and A which indicates the poor quality of the groundwater around this area.

Evaluation of microbiological and physicochemical indicators for wastewater treatment.

The quality control of wastewater treatments was monitored using selected novel and classical physicochemical and microbiological indicators, and the associations of the treatments with the effluents was analyzed. The microbiological indicators monitored were heterotrophic plate count (HPC), total coliforms (TC), fecal coliforms (FC), fecal streptococci (FS), sulfite-reducing clostridia (SRC), Pseudomonas aeruginosa, and Salmonella spp. The stages of wastewater treatment also were evaluated through determination of ammonia; biological oxygen demand (BOD(5)); chemical oxygen demand (COD); chloride; conductivity; suspended dissolved and total solids; fats; nitrate, nitrite, and total nitrogen; pH; phosphate and total phosphorus. Additional indicators included the Escherichia coli growth inhibition (IGEC) bioassay for assessing whole effluent toxicity, spectral determinations between wavelengths (lambda) 190-650 nm, and total (TP) and soluble (SP) protein contents. Of the more common physicochemical parameters, only BOD(5), COD, suspended and total solids, and fats showed a statistically significant reduction between raw water and effluent; for the microbiological indicators, significant reduction was seen only for HPC, FC, and Ps. aeruginosa. We suggest that determinations of Ps. aeruginosa be commonly used as an indicator of wastewater quality. Spectral analysis--most notably the values of absorbance at 225, 255, and 295 nm-revealed a statistically significant correlation with several physicochemical parameters. Statistical analysis of SP and TP values showed them to be good indicators of contamination. The quantitative study of Salmonella spp. and the results of the IGEC bioassay show the need for close control of infectious and toxic risks in wastewater and effluents.

[Hygienic evaluation of oxygen produced in a system using solid polymer electrolytes]. / Gigienicheskaia otsenka kisloroda, poluchennogo v sisteme s tverdym polimernym élektrolitom.

It has been shown that gaseous oxygen produced in a system containing a solid polymer electrolyte from distilled water and two water samples containing different concentrations of chemicals meets on the whole USSR Standard 5583-78 and iso standard 2046. This oxygen underwent toxic evaluations on 60 white noninbred male rats. When mixed with gaseous nitrogen (1:4), electrolytically produced oxygen exerted no unfavorable effects on the animals.

A rapid method for the quantification of C, N and O in biomedical samples by proton-induced gamma-ray emission analysis applied to human placental samples.

A new fast, accurate and simple quantification method for C, N and O in biomedical samples by external-beam proton-induced gamma-ray emission analysis is presented. Concentration values for C, N and O in commercial standards of NBS bovine liver 1577a, IAEA animal muscle H-4 and IAEA horse kidney H-8 were determined using the new method. The concentrations of C, N, O, Na, Mg and P were determined from placental samples of 13 alcoholic mothers and from 16 abstinent controls. The values obtained for C, N, O, Mg and P were the first values ever obtained for human placentas.